MODELING THE GROWTH, SURVIVAL AND DEATH OF LISTERIA-MONOCYTOGENES

In this paper, the predictive microbiology approach has been generaliz ed to the study of growth, survival and death of Listeria monocytogene s. As this micro-organism is involved in food poisoning, its growth, s urvival and death were studied as functions of low temperatures, NaCl and phenol compounds, in a synthetic medium, by a factorially designed experiment. A significant inactivation of L. monocytogenes was obtain ed with 20 ppm of phenol and 4% (w/v) NaCl at temperatures from 4 to 1 2 degrees C. An empirical model is proposed to describe, in a single s tep, the biomass profile cs studied factors. Thereby, the influence of temperature, NaCl and phenol concentration on L. Monocytogenes biomas s quantity (0.5-8 log cfu ml(-1)) are presented as a function of stora ge duration. The comparisons of the proposed model with existing model s (Gompertz for growth, vitalistic for survival and death) were perfor med. The use of a single equation allows the prediction of contaminati on levels in all experimental conditions without knowledge a priori. T he model offers considerable prospects for its use in food microbiolog y.